Black-capped Chickadees (Poecile atricapillus) can identify individual females by their fee-bee songs

ABSTRACT Individual recognition is a social behavior that occurs in many bird species. A bird's ability to discriminate among familiar and unfamiliar conspecifics is critical to avoid wasting resources such as time and energy during social interactions. Black-capped Chickadees (Poecile atricapillus) are able to discriminate individual female and male chick-a-dee calls, potentially male and female tseet calls, and male fee-bee songs. In the current study, we used an operant discrimination go/no-go paradigm to determine whether female and male chickadees could discriminate between fee-bee songs produced by individual female chickadees as well as test which song component(s) enable this discrimination. Birds trained on natural categories—the songs of different females—learned to respond to rewarded stimuli more quickly than birds trained on random groupings of female songs and were able to transfer this learning to new songs from the same categories. Chickadees were also able to generalize their responding when exposed to the bee note of the fee-bee song of rewarded individuals; they did not generalize to fee notes. Our results provide evidence that Black-capped Chickadees can use female-produced fee-bee songs for individual recognition. However, the acoustic features underlying individual recognition require further investigation. LAY SUMMARY The current study used an operant conditioning paradigm to test whether Black-capped Chickadees can distinguish between the songs of individual female Black-capped Chickadees. Research on female song in Black-capped Chickadees has shown that female song differs from male song in sound and perception, and chickadees can distinguish between male and female song. We found that male and female chickadees can distinguish between females by listening to their song, and can do so using the whole song and only part of the song. A chickadee's ability to distinguish song by sex as well as by the individual female suggests that female song does serve a function in Black-capped Chickadees.